Purification of wood sugar



Patented June 21, 1932 UNITED STATES IPATENT OFFICE I EDUARD Fianna, or nnl nmnnne, enimauv, 'assrenon T iiOLZHYDIB/OLYSE Ax'rmu- GEBELLSCHAFT, or ntann snae, ennmmr pennies-non or'woon seem No Drawing. Application filed July 6, 1929,8eria1 No. 376,502,-

in Germany-July 7, 1928; l

Wood sugar, which is obtained by the hydrolysis of wood with concentrated hydrochloric acid, may be -freed, to a very large extent, from the excess hydrochloric acid if 5 the wood sugar solution in a finely atomized state is brought into contact with a hotcurrent of air '(see U. S. A. patent specification No. 1,678,819). The so-called dry-sugar obtained in this way still'posscsses two undesirable properties; it isa light, voluminous powder-consisting of particles of irregular shapes and large surfaces, which is therefore, ill-suited for transport and further working up, and also it contains resinous impurities 1 and always remnants of hydrochloric acid, which are detrimental for many purposes.

The removal of both of these disadvantages in a technically advantageous manner is the object of the invention. I I

2 It might be contemplated to wash out the impurities of the dry sugar withorganic solvents, such as alcohol, acetic anhydride and the like. The dry sugar, however, holds firmly in its pores large quantities of added nonaqueous liquids. Thus, 95% alcohol must be added in a quantity up to four times the Weight of the product before any of it drains oii. Moreover, even when still larger quantities of alcohol are 'used,'the alcohol draining off contains only very little of the hydrochloric acid which is present in the crude product to be purified. Only by washing out the alcohol retained bythe mass can considerable quantities of hydrochloric acid be brought into solution. However, it is not economical to work in this manner; the loss in sugar is considerable, the waste of alcohol is too great and its recovery too costly.,

According to the present invention, over 49 80% of the hydrochloric acid'present in the dry sugar can be separated by means of certain organic solvents by mere d'ecantation of the same from the sugar and simultaneously the sugar is converted into a syrup of high specific gravity. The organic solvents suitable for this purpose are organic liquids containing oxygen which dissolve hydrochloric acid readily and sugar with difficulty. They are soluble in water. The separation of sugar and hydrochloric acid may,

for instance, be attained by gently heating the mixture of'sugar and solvent.' The loose sugar thereby sinters together and the solvent used may then be easily and almost com.-

-pletely poured off. The degree of heating 6|! necessary dependson the. nature of the solvent and on its water content,

A mixture of 95 %'alcohol with benzene in the ratio of 5: 1 has proved to be particularly suitabld It is then suflicient to 'heat the mixture to 50--6 0. inorder to produce the desired sintering. The presence of benzene depresses the solubility of the sugar in alcohol and raises its absorption capability for the resinous extraneous constituents of the dry-sugar, I The separation of sugar and solvent and the simultaneous conversion of the sugar'into a syrup form may also be attained by adding a 7 small quantity of water to the mixture of sugar and aIeohoLbenZene. If the dry sugar werelfirst to be taken up with water and the syrup obtained treated with alcohol-benzene mixture, the original large surface of the dry sugar, otherwise firmly retaining the organic 75 solvent, would indeed be destoyed: however, at the same time, the partition coeflieient of the hydrogen chloride between the water in' the syrupand the organic solvent would be displaced in an unfavorable direction so so that much sugar would go into solution with but little hydrochloric acid. It would not be practical therefore to work in this manner. When the dry sugar contains chlorides besides free hydrochloric acid, it is of great 95 value to remove these chlorine ions also. This may be effected byadding fairly, a. small quantity of concentrated sulphuric acid to the solvent.

Ewamples 9 1. 1000 guns. of dry sugar obtained by hydrolyzing wood with-hydrochloric acid are stirred up at ordinary temperature with 3 litres of a mixture containing 1 part of 95% 95 alcohol and 0.2 part of benzene together with 10 gms. of concentrated sulphuric acid; after standing a short while the whole is heated to and then the solvent is poured off; The latter. contains 30 gms; H01 and 31 guns. of 9 sugar, the sugar sugar and 0.3%

present being calculated as hydrochloric acid), besides about 13% of water and 18.7% of alcohol mixed with benzene. Thus, about 2.8 litres of the solvent mixture used have been poured olf.

2. 1000 gms. of dry sugar obtained by bydrolyzing wood with hydrochloric acid are stirred up with 4 litresof the above mixture. After a short time, about 200 cc. of water are added in a finely divided state, whereupon the previously pulverized sugar goes over into syrup. The solvent contains 29 gms. .HCl and 40 gms. of sugar, and the syrup, 62% sugar and 0.3% HCl, besides about of water and 17.7% of alcohol-benzene. Thus,

' about 3.7 litres of the alcohol-benzene mix ture have been poured oil.

What I claim is z 1. A process for purifying wood sugar obtained by hydrolyzing wood and other substances containing cellulose with hydrochloric acid, consisting in drying the wood sugar by atomization, removing the hydrochloric acid by-treating the resulting crude powder. with a solvent comprising an alcohol, converting the crude product into a syrup, and removing the solvent.

2. A process for purifying wood sugar obtained by hydrolyzing wood and other substances containing cellulose with hydrochloric acid, consisting in drying the wood sugar by atomization, removing the hydrochloric acid by treating the resulting crude powder with a solvent comprising an alcohol,

sintering the crude product by gently heating the mixture, and removing the solvent.

3. A process for purifying wood sugar obtained by hydrolyzing wood and other substances containingcellulose with hydrochloric acid, consisting in drying the wood sugar by atomization, treating the loose crude powder obtained with a mixture of alcohol and benzene, converting the crude product into a syrup, and removing the solvent.

4. A process for purifying wood sugar obtained by hydrolyzing wood and other substances containing cellulose with hydrochloric acid, consisting in drying the wood sugar by atomization, treating the loose crude powder obtained with a mixture of alcohol and benzene, sintering the crude product by gently heating the mixture, and removing the solvent.

5. A process for purifying wood sugar obtained by hydrolyzing wood and other substances containing cellulose with hydrochloric acid,,consisting in drying the wood sugar by atomization, treating the loose crude powder obtained with a mixture of 5'parts of y 95% alcohol and 1 part of benzene, converting the crude product into a syrup,'and removlng the solvent.

6. A process for purifying wood sugar obtained by hydrolyzing wood and other substances containing cellulose with hydrochloric acid, consisting in drying the wood sugar by atomization, treating the loose crude powder obtained With a mixture of 5 parts of 95% alcohol and 1 part of benzene, sintering the crude product by gently heating the mixture, and removing the solvent.

7. A process for purifying wood sugar obtained by hydrolyzing wood and other substances containing cellulose with hydrochloric acid, consisting in' drying the wood sugar by atomization, treating the loose crude powder obtained with a mixture of 5 parts of 95% alcohol and 1 part of benzene, sintering the crude produce by heating the mixture to 50(50 (3., and removing the solvent.

8. A process for purifying wood sugar obtained by hydrolyzing wood and other substances containing cellulose with hydrochloric acid, consisting in drying the wood sugar by atomization, treating the loose crude powder obtained with organic solvents containing oxygen which are capableof readily dissolving hydrochloric acid and which dissolve wood sugar with (lifliculty, and sintering the crude product and separating the solvent with the impurities by adding a small quantity of water to the mixture.

9. A process for purifying wood sugar obtained by hydrolyzing wood and other substances containing cellulose with hydrochloric acid, consisting in drying the woodsugar by atomization, treating the loose crude powder obtained with a' mixture of alcohol and benzene, and sintering the crude product and separating the solvent with the impurities by adding a small quantity of water to the mixture.

10. A process as claimed in claim 1 and in which a small quantity of concentrated sulphuric acid is added to the solvent.

In testimony whereof I havesigned my name to this specification.

EDUAR-D FARBER. 

